scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Phytochelatins and their roles in heavy metal detoxification

01 Jul 2000-Plant Physiology (American Society of Plant Biologists)-Vol. 123, Iss: 3, pp 825-832
TL;DR: Plants respond to heavy metal toxicity in a variety of different ways, including immobilization, exclusion, chelation and compartmentalization of the metal ions, and the expression of more general stress response mechanisms such as ethylene and stress proteins.
Abstract: Plants respond to heavy metal toxicity in a variety of different ways. Such responses include immobilization, exclusion, chelation and compartmentalization of the metal ions, and the expression of more general stress response mechanisms such as ethylene and stress proteins. These mechanisms have

Content maybe subject to copyright    Report

Citations
More filters
Journal ArticleDOI
TL;DR: Recent advances in understanding the regulation of PC biosynthesis and MT gene expression and the possible roles of PCs and MTs in heavy metal detoxification and homeostasis are reviewed.
Abstract: ▪ Abstract Among the heavy metal-binding ligands in plant cells the phytochelatins (PCs) and metallothioneins (MTs) are the best characterized. PCs and MTs are different classes of cysteine-rich, heavy metal-binding protein molecules. PCs are enzymatically synthesized peptides, whereas MTs are gene-encoded polypeptides. Recently, genes encoding the enzyme PC synthase have been identified in plants and other species while the completion of the Arabidopsis genome sequence has allowed the identification of the entire suite of MT genes in a higher plant. Recent advances in understanding the regulation of PC biosynthesis and MT gene expression and the possible roles of PCs and MTs in heavy metal detoxification and homeostasis are reviewed.

2,334 citations

Journal ArticleDOI
01 Mar 2001-Planta
TL;DR: Recent progress in the molecular understanding of plant metal homeostasis and tolerance is reviewed and a number of uptake transporters have been cloned as well as candidates for the vacuolar sequestration of metals are identified.
Abstract: Transition metals such as copper are essential for many physiological processes yet can be toxic at elevated levels. Other metals (e.g. lead) are nonessential and potentially highly toxic. Plants – like all other organisms – possess homeostatic mechanisms to maintain the correct concentrations of essential metal ions in different cellular compartments and to minimize the damage from exposure to nonessential metal ions. A regulated network of metal transport, chelation, trafficking and sequestration activities functions to provide the uptake, distribution and detoxification of metal ions. Some of the components of this network have now been identified: a number of uptake transporters have been cloned as well as candidate transporters for the vacuolar sequestration of metals. Chelators and chaperones are known, and evidence for intracellular metal trafficking is emerging. This recent progress in the molecular understanding of plant metal homeostasis and tolerance is reviewed.

1,327 citations

Journal ArticleDOI
TL;DR: Some plants can hyperaccumulate metal ions that are toxic to virtually all other organisms at low dosages, and this trait could be used to clean up metal-contaminated soils.

1,180 citations

Journal ArticleDOI
TL;DR: This review deals with N-containing metabolites frequently preferentially synthesized under heavy metal stress such as Cd, Cu, Ni, and Zn, with special focus on proline and certain other amino acids and oligopeptides, as well as betaine, polyamines, and nicotianamine.
Abstract: Plants exposed to heavy metals accumulate an array of metabolites, some to high millimolar concentrations. This review deals with N-containing metabolites frequently preferentially synthesized under heavy metal stress such as Cd, Cu, Ni, and Zn. Special focus is given to proline, but certain other amino acids and oligopeptides, as well as betaine, polyamines, and nicotianamine are also addressed. Particularly for proline a large body of data suggests significant beneficial functions under metal stress. In general, the molecules have three major functions, namely metal binding, antioxidant defence, and signalling. Strong correlative and mechanistic experimental evidence, including work with transgenic plants and algae, has been provided that indicates the involvement of metal-induced proline in metal stress defence. Histidine, other amino acids and particularly phytochelatins and glutathione play a role in metal binding, while polyamines function as signalling molecules and antioxidants. Their accumulation needs to be considered as active response and not as consequence of metabolic dys-regulation.

1,142 citations


Cites background from "Phytochelatins and their roles in h..."

  • ...From a variety of experimental approaches the involvement of PCs in the detoxification of Cd and As (Cobbett, 2000,; Schmöger et al., 2000) appears definite as they could also be linked to the differential heritable tolerance to Cd in Arabidopsis thaliana (Howden et al., 1995) and As in Holcus…...

    [...]

  • ...From a variety of experimental approaches the involvement of PCs in the detoxification of Cd and As ( Cobbett, 2000, ; Schmo ¨ger et al., 2000) appears definite as they could also be linked to the differential heritable tolerance to Cd in Arabidopsis thaliana (Howden et al., 1995) and As in Holcus lanatus (Hartley-Whitaker et al., 2001)....

    [...]

Journal ArticleDOI
TL;DR: The mobility, bioavaliability and plant response to presence of soil heavy metals, classifies the plants according to phytoextraction mechanism and discusses the pathway of metal in plants.
Abstract: This review presents the status of phytoremediation technologies with particular emphasis on phytoextraction of soil heavy metal contamination. Unlike organic compounds, metals cannot be degraded, and cleanup usually requires their removal. Most of the conventional remedial technologies are expensive and inhibit the soil fertility; this subsequently causes negative impacts on the ecosystem. Phytoremediation is a cost effective, environmental friendly, aesthetically pleasing approach most suitable for developing countries. Despite this potential, phytoremediation is yet to become a commercially available technology in India. This paper reports about the mobility, bioavaliability and plant response to presence of soil heavy metals. It classifies the plants according to phytoextraction mechanism and discusses the pathway of metal in plants. Various techniques to enhance phytoextraction and utilization of by-products have been elaborated. Since lot of biomass is produced during this process, it needs proper disposal and management. It also gives an insight into the work done by authors, which focuses on high biomass extractor plants. High biomas weeds were selected to restrict the passage of contaminants into the food chain by selecting non-edible, disease resistant and tolerant plants, which can provide renewable energy. Thus making phytoextraction more viable for present utilization. Keywords. heavy metals, phytoextraction, hyperaccumulator, indicator, excluder species

1,096 citations


Cites background from "Phytochelatins and their roles in h..."

  • ...Induced Phytoextraction or Chelate assisted Phytoextraction Within the plant cell heavy metal may trigger the production of oligopeptide ligands known as phytochelatins (PCs) and metallothioneins (MTs) [67]....

    [...]

References
More filters
Journal ArticleDOI
01 Jun 1998
TL;DR: A detailed account of current knowledge of the biosynthesis, compartmentation, and transport of these two important antioxidants, with emphasis on the unique insights and advances gained by molecular exploration are provided.
Abstract: To cope with environmental fluctuations and to prevent invasion by pathogens, plant metabolism must be flexible and dynamic. Active oxygen species, whose formation is accelerated under stress conditions, must be rapidly processed if oxidative damage is to be averted. The lifetime of active oxygen species within the cellular environment is determined by the antioxidative system, which provides crucial protection against oxidative damage. The antioxidative system comprises numerous enzymes and compounds of low molecular weight. While research into the former has benefited greatly from advances in molecular technology, the pathways by which the latter are synthesized have received comparatively little attention. The present review emphasizes the roles of ascorbate and glutathione in plant metabolism and stress tolerance. We provide a detailed account of current knowledge of the biosynthesis, compartmentation, and transport of these two important antioxidants, with emphasis on the unique insights and advances gained by molecular exploration.

5,450 citations


"Phytochelatins and their roles in h..." refers background in this paper

  • ...There is also circumstantial evidence supporting post-transcriptional regulation of GCS expression in addition to the well-recognized regulation of GCS activity through GSH feedback inhibition (May et al., 1998; Noctor and Foyer, 1998)....

    [...]

Journal ArticleDOI
TL;DR: It is proposed that, above all in response to acute cadmium stress, various mechanisms might operate both in an additive and in a potentiating way, and a holistic and integrated approach seems to be necessary in the study of the response of higher plants to Cadmium.

2,189 citations

Journal ArticleDOI
TL;DR: Recent progress that has been made in the understanding of Al toxicity and the mechanisms of Al tolerance in plants are reviewed.
Abstract: Aluminum (Al) is the most abundant metal in the earth's crust, comprising about 7% of its mass. Since many plant species are sensitive to micromolar concentrations of Al, the potential for soils to be Al toxic is considerable. Fortunately, most of the Al is bound by ligands or occurs in other nonphytotoxic forms such as aluminosilicates and precipitates. However, solubilization of this Al is enhanced by low pH and Al toxicity is a major factor limiting plant production on acid soils. Soil acidification can develop naturally when basic cations are leached from soils, but it can be accelerated by some farming practices and by acid rain (Kennedy, 1986). Strategies to maintain production on these soils include the application of lime to raise the soil pH and the use of plants that are tolerant of acid soils. Although Al toxicity has been identified as a problem of acid soils for over 70 years, our knowledge about the primary sites of toxicity and the chain of events that finally affects plant growth remains largely speculative. In this paper we review recent progress that has been made in our understanding of Al toxicity and the mechanisms of Al tolerance in plants.

1,242 citations

Journal ArticleDOI
01 Jan 1996-Gene
TL;DR: The isolation of a Cd(2+)-sensitive cadl mutant of Arabidopsis thaliana, that is deficient in PC synthase, demonstrates conclusively the importance of PC for heavy metal tolerance.

1,001 citations


"Phytochelatins and their roles in h..." refers background in this paper

  • ...In addition, a number of structural variants, for example, (g-Glu-Cys)n-bAla, (g-Glu-Cys)n-Ser, and (g-Glu-Cys)n-Glu, have been identified in some plant species (Rauser, 1995, 1999; Zenk, 1996)....

    [...]

  • ...Numerous physiological, biochemical, and genetic studies have confirmed that GSH (or, in some cases, related compounds) is the substrate for PC biosynthesis (Rauser, 1995, 1999; Zenk, 1996)....

    [...]

  • ...Other more recent reviews are by Zenk (1996) and Rauser (1999)....

    [...]

  • ...These observations have been interpreted to indicate a role for PCs in the homeostasis of essential metal ion metabolism (Rauser, 1995, 1999; Zenk, 1996)....

    [...]

  • ...In addition, roles for PCs in Fe or sulfur metabolism have also been proposed (Zenk, 1996; Sanita di Toppi and Gabbrielli, 1999)....

    [...]

Journal ArticleDOI
TL;DR: An enzyme has been discovered and characterized from Silene cucubalus cell suspension cultures that catalyzes the transfer of the gamma-glutamylcysteine dipeptide moiety of glutathione to an acceptors molecule or a growing chain of [Glu(-Cys)](n)-Gly oligomers, thus synthesizing phytochelatins, the metal-binding peptides of higher plants and select fungi.
Abstract: An enzyme has been discovered and characterized from Silene cucubalus cell suspension cultures that catalyzes the transfer of the γ-glutamylcysteine dipeptide moiety of glutathione to an acceptor glutathione molecule or a growing chain of [Glu(-Cys)]n-Gly oligomers, thus synthesizing phytochelatins, the metal-binding peptides of higher plants and select fungi. The enzyme was named γ-glutamylcysteine dipeptidyl transpeptidase and given the trivial name phytochelatin synthase. The primary reaction catalyzed is [Glu(-Cys)]-Gly + [Glu(-Cys)]n-Gly → [Glu(-Cys)]n+1-Gly + Gly. The enzyme is isoelectric near pH 4.8 and has temperature and pH optima at 35°C and 7.9, respectively. Phytochelatin synthase is constitutively present in cell cultures of various plant species and its formation is not noticeably induced by heavy metal ions in the growth medium. The enzyme (Mr95,000) seems to be composed of four subunits, the dimer (Mr50,000) being also catalytically active. Cd2+ is by far the best metal activator of the enzyme followed by Ag+, Bi3+, Pb2+, Zn2+, Cu2+, Hg2+, and Au+. The Km for glutathione is 6.7 mM. The enzyme activity seems to be self-regulated in that the product of the reaction (the phytochelatins) chelates the enzyme-activating metal, thus terminating the enzyme reaction. The molar ratio of the γ-glutamylcysteine dipeptide in phytochelatin to Cd2+ in the newly formed complex was 2:1.

892 citations


"Phytochelatins and their roles in h..." refers background in this paper

  • ...Grill et al. (1989) first identified an enzyme activity from cultured cells of Silene cucubalis that synthesized PCs from GSH by transferring a g-Glu-Cys moiety from a donor to an acceptor molecule....

    [...]

  • ...It has been detected in S. cucubalis cells grown in culture medium (Grill et al., 1989), and in tomato (Chen et al., 1997) and Arabidopsis (Howden et al., 1995) plants grown in soil or agar medium, in the presence of only trace levels of essential heavy metals....

    [...]